Use of the Electrokinetic Process to Improve Phytoremediation

The efficient removal or permanent immobilization of metals achieved by current techniques such as physical extraction, chemical leaching, and vitrification results in both soil structure and fertility detriment. On the other hand, remediation technologies based on biological systems (bioremediation and phytoremediation) seem to be sound processes that enhance the natural response of soil to heavy metal contamination. In these cases, the slow rates of heavy metal removal in soil are strong drawbacks to scaling up the processes for technological applications. 

In past decades, the development of phytoremediation techniques has faced several limitations because of hyperaccumulators low rate of growth and biomass production. Also, soil conditions do not always favor metal extraction by plant roots 

Lim et al. (2004) optimized the time and electric field applied to each Indian mustard Brassica juncea) plant in a remediation experiment performed in 1.2-kg pots of lead- and arsenic-contaminated soil. The electric potential of 30-40V applied 1 h per day were the optimal conditions to reach maximum phytoextraction after 9-day treatment. In this case, the increase of EDTA availability by the electrical current caused a rapid toxicity response of plants that limited the remediation process. 

Since the electric field efficiently drives increased amounts of soluble heavy metals toward plant roots, which results in stress conditions for plants, hyperaccumulator plants with a rapid growth period are candidates for use in combination 

In light of the results obtained from this preliminary assay to the combined technology, several aspects still need to be adjusted. Changes in the polarity of electrodes during the process can avoid fixed redistribution of heavy metals and soil pH values that are associated with different rates of plant biomass and phytoextractions to the proximity to electrodes. The combined technique is homogenously applied to the contaminated site. 

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